[CI] check-links: update code to push refcache etc (open-telemetry#6147)

Author: chalin

.github/workflows/check-links.yml

@@ -5,6 +5,12 @@ on:
   merge_group:
   pull_request:
 
+env:
+  CHANGED_FILES:
+  PR_NUM: ${{ github.event.issue.number }}
+  USER_EMAIL: [email protected]
+  USER_NAME: opentelemetrybot
+
 jobs:
   build-and-check-links:
     name: BUILD and CHECK LINKS
@@ -43,29 +49,41 @@ jobs:
           echo "submodule(s); or undo the submodule update(s) if it happened by mistake."
           npm run _diff:fail
 
-      - run: npm run log:check:links
+      - run: |
+          npm run log:check:links
+          CHANGED_FILES=$(git status --porcelain)
+          echo "CHANGED_FILES=$CHANGED_FILES" >> "$GITHUB_ENV"
         continue-on-error: true
 
       - name: Push changes if any, and fail check
+        if: ${{ env.CHANGED_FILES }}
         run: |
-          if [[ $(git status --porcelain) ]]; then
-            echo "Changes detected in the refcache etc:"
-            git status --short
-
-            echo "\nPushing changes to PR."
-            git config --local user.email "$USER_EMAIL"
-            git config --local user.name "$USER_NAME"
-            git add -A
-            git commit -m "Updates from build-and-check-links workflow"
-            git push
-
-            echo "Failing workflow so that changes can be reviewed, and checks rerun."
-            exit 1
-          fi
+          echo "Changes detected in the refcache etc:"
+          git status --short
+
+          gh pr checkout $PR_NUM -b "pr-check-links-${RANDOM}"
+          git branch -v
+
+          git config --local user.email "$USER_EMAIL"
+          git config --local user.name "$USER_NAME"
+          git add -A
+          git commit -m "Updates from build-and-check-links workflow"
+
+          echo "\nPushing changes to PR."
+          current_branch=$(git rev-parse --abbrev-ref HEAD)
+          echo current_branch=$current_branch
+          # gh pr checkout sets some git configs that we can use to make sure
+          # we push to the right repo & to the right branch
+          remote_repo=$(git config --get branch.${current_branch}.remote)
+          echo remote_repo=$remote_repo
+          remote_branch=$(git config --get branch.${current_branch}.merge)
+          echo remote_branch=$remote_branch
+          git push ${remote_repo} HEAD:${remote_branch}
+
+          echo "Failing workflow so that changes can be reviewed, and checks rerun."
+          exit 1
         env:
           GH_TOKEN: ${{ secrets.OPENTELEMETRYBOT_GITHUB_TOKEN }}
-          USER_EMAIL: [email protected]
-          USER_NAME: opentelemetrybot
 
       - uses: actions/upload-artifact@v4
         with: